<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<script>
    function A1(){
    }
    A1.prototype.say= function () {
        alert("a1")
    };
    function A2(){
        this.age=8;
    }
    A2.prototype=new A1();
    A2.prototype.sayTwo= function () {
      alert("a2")
    };
    var a3=new A2();
    var a1=new A1();
    a3.say();
    a3.sayTwo();
    alert('ds');
</script>
</body>
</html>